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W. 6; R. AITKEN.

SEMI AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATlON FILED DEC. 23. m4.

1 1 95,89 1 Patented Aug. 22, 1916.

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W. & R. AITKEN. SEMI-AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED DEC-21%| 19H- 3 SHEETS-SHEET 2- Patented Aug. 22;

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W. & R. AITKEN.

SEMI-AUTOMATIC TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED DEC. 23, 1914- 1 1 95,89 1 Patented A11 22, 1916.

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WILLIAM AITKEN AND ROBERT AITK EN, OF LONDON, ENGLAND.

SEMI-AUTOMATIC TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent. Patented Aug. 22, 1916.

Application fi1ed.December 23, 1914. Serial No. 878,761.

To all whom it may concern:

Be it known that weflViLLriM ArrxnN and Ronnn'r Arrxnx, subjects of the King of (Treat Britain and Ireland, residing in London, England, have invented certain new and useful Improvement in Semi-Automatic 'lclephone-Exchange Systems, of which the following is a specification.

This invention relates to telephone systems and more particularly to manually operated or semi-autonnitic telephone systems in which the junctions, or exchange interconnecting lines, are worked automatically without the use oi, (or, in certain cases very limited use of) dial, push-button, or other pattern of keyboard calling device. By such an arrangement the operators work would be similar to the present manual methods. The plugging into a jack however would select an idle junction line appropriate to the connection to be built up, and connect an automatically operated or in ciiinddriren impulse sending device which would interrupt the circuit intermittently according to a code which will operate selectors, or other automatic switches, to call an o )erator at the exchange wanted.

The invention is illustrated by three sheets of drawin s in which Figure 1 shows a typical lay-out of a large telephone area. Fig. 2 a diagrammatic representation of the circuits through certain exchanges or" such an area. Fig. 3 is a section of a machine-driven impulse-sender.

Fig. i an elevation of the Same. Fig. 5 a diagram of one arrangement of circuits tor the above impulse-sender.

in a large telephone area as represented in Fig. 1 for economical reasons it is advisable to ut' ctions having a light gage or? ccper r conversation hetween adjacent exchang s when they are only a short distance apart, or between groups of local exchanges. medium when the exchanges are farther apart, or the conversation is through two or more intermediate exchanges, and heavy gage copper when the exchanges are on the opposite sides of an area and for connections to the trunk or long distance exchange. In such an area it would be impossible for operators to correctly route and select the proper gage of wire for through connections and it is the object of this invention to do this automatically without the knowledge or assistance of the operator.

In Fig. l, G represent exchanges in the center of the area, T the trunk exchange. W S N and E are large exchanges which also fulfil the part of junction line connecting exchanges, and around these are grouped subordinate exchanges. Around the fringe of the area are shown small exchanges designated by M whichare not important enough in all cases or have not proper facilities to warrant the introduction of machinedriven impulse-senders. Between certain exchanges, as for example and M, only light gage wires are shown as available. It is reckoned that the short length of light gage would not appreciably depreciate the transmission, say when through to the trunk exchange because heavy gage wire would be utilized beyond W M talking to M might still utilize light wires, when talking to Vi might use medium gage, and when talking to trunk or central and beyond would use heavy gage wires. Exchange W has light gage wires to talk to the central, medium to talk to N or S and exchanges immediately connected therewith, and heavy wires for connections beyond these and to the trunk exchange, Exchanges W S E and others similarly situated are shown with all three gages to allow them good facilities for reaching all exchanges in the area. In an area laid out in this way it is not necessary to run direct lines to different exchanges from one point as is the practice at present. The junctions should run from ex change to exchange only and be multipled on the banks of selectors or other automatic switches so as to be available to a large number of exchanges. Connections to the trunk exchange from outlying exchanges would be obtained through the junction centrals C, N, S, E, W. l Vhere an instantaneous service is given over a large number of long unctions or trunks. arrangements can be made for calling through the trunk exchange and building up a continuous circuit to an exchange beyond by fitting a repeater or intermediate impulse sending de vice, which'would send out additional impulses or repeat a. desired code. I

F ig. 2 shows the switching arrangements, circuits however being represented by single lines. Exchange W is the exchange selected to illustrate our invention. At is shown a multiple board consisting of a mul tiple of three sections, three lines being shown in each multiple in the length and four multiples for junction lines in the height and a level of multiples for subscribers lines. The signaling circuits only are shown, and the circles indicate the bush of the jacks on which they end. P to P represent incoming junctions from small outlying exchanges, and P P"=, P 'P are plug units for connecting subscribers lines to outgoing junctions or jack ending lines from small exchanges to outgoing junctions. IE to KS are impulse senders one being associated with each outgoing junction line. These are machine-driven and electrically controlled in such a way that when a plug is inserted in a ack a disk revolves and opens the line circuit a predetermined number of times to actuate an automatic switch at a distance. These will be described more in detail later. S to S are subscribers lines which have signaling lamps L to L and terminate on multiple jacks J to J Above W is shown apparatus located at several exchanges the designating letters corresponding to the letters in Fig. 1. The automatic s "itch repre sented is of the Strowger type with vertical and rotary movements. A side view is indicated so that the horizontal lines represent bank levels in which there are usually ten circuits. All circuits on a level are of the same gage conductor but different levels may have different gages. a is the shaft carrying the wipers I) which make contact with the bank contacts 0. Firm lines in Figs. 1 and 2 indicate heavy gage circuits. dot and dash lines medium conductors, and dotted lines light gage circuits. M repre sents a small manual exchange in which con nections may be obtained over a direct circuit J to Vi where the connection would be manually completed and the remainder built up automatically. M has an alternative arrangement, an impulse-sender of the dial, push button or other type being fitted so that the operator can call automatically and build up any connection desired. lvl represents a small exchange which has no automatic apparatus whatever, the operator taking the de nands orally and V making connections which build up the remainder of the connection automatically. W is in exchange having machine-driven impulse senders. The junction line J L is shown connected to two impulse-senders 1S and IS, and to two jacks J, J in parallel. It is supposed that there are only a small number of junction lines available and that a large proportion of the calls are to two exchanges, for example, VW and trunk T. The two senders have different codes so that if the operator inserts the plug in jack J she will connect with but if the plug is inserted in ack J the trunk exchange will be caller Three or more exchanges may be called over one wire in the same way.

Jacks and impulse-senders and some connection with an automatic line switch will be provided for every exchange that may be connected with, but only junctions suiiicient to carry the traflic will be necessary, these being subdivided according to the traffie to exchanges having light, medium and heavy gage junctions. The jack or multiple of acks associated with an exchange will be suitably labeled with the code of the exchange although it has no direct circuit thereto. For example, if subscriber S of V calls for a number in exchange M the operator, having already inserted the plug P in J to answer, inserts P in jack M The line switch of the Strowger type would connect with a preselected idle junction of a group having all lines of a particular gage of conductor. The impulse-sender which may be connected in parallel with the line switch or be in a local circuit completed by it will also be energized and open the circuit according to a code (to be described later) to cause the shaft (4 of a selector W at the exchange .V to lift the wipers 7), in this case to the fourth level. The wipers then rotate automatically to select an idle line and make contact with the bank spring 0. The line is thus extended to the exchange N where the selector acts in a similar manner again rising to the fourth level, according to the predetermined code of the sender, ant. the line is further extended to N where the wipers make contact on the first level. N is next operated and connects with the third level when the lamp L at exchange M glows as a calling signal. The code on the impulsesender for M is 4413. if the jack marked T had been plugged into a heavy gage junction would again have been selected but as the sender code is one impulse W at W connects on the first level and the lamp LT glows at the trunk exchange. If jack C is plugged into, the line switch of which is in a group having medium gage junctions to the 3 exchange, code 1 on W raises it to the first level and the lamp LC glows at C. A connection in exchange lV may be obtained by the line switch at 3V connected to jack .4 glowing a lamp directly at V], or a selector W be raised to the fifth level to glow the lamp. Ml" is called in a. manner already described the code being 34 If M is wanted the jack so labeled would be plugged into and the code M ll would call into exchange E where a line would be selected in which there is a second impulse sender which would send additional impulses to call into M and glow the lamp L the additional code being 321. Should subscriber S on M desire connection with, say C, the operator would insert the plugs P, P in jacks J, J and manipulate the dial 15 for two digits, or P Would be inserted in J and the;

operator at 1V asked to complete the concction by inserting the plug P in jack C. In a similar manner M would connect S by plugs P, P in jacks J, J* and plug P in jack C. Lamp L is the calling signal at for. exchange M S on Vi would be connected by plugs P P in jacks J and J or J to call into one of two exchanges by means of selector -WS.

Selectors and line switches of the Strowger type have been described but any other type may be used. The line switches of the type which finds the calling line might advantageously be used preferably located at the originating exchange with branch lines between the jacks and the bank contacts so that the switch would pick out the operator calling, in a well-known manner. The manual exchanges referred to may be of the common battery type where the operator disconnects on the two supervisory signals being displayed, or they may be of the type in which the cords are rendered electrically inoperative or disconnected when the calling, or calling and called subscribers replace the receivers after conversation.

All or some of the exchanges may be equipped with automatic apparatus so that for incoming calls the subscriber wanted may be called by the operator at the origi nating exc wage or other controlling exchange manipulating a dial or other form of impulse sender, or may be called by the callin; 'ubscriber manipulating such a calldevice which is fitted in connection with his instrument. In such an arrangement the subscriber would lift the receiver to glow a lamp as a calling signal as at present, and give the operator the name only of the exchange wanted. The operator by inserting the plug in the jack associated with that exchange would automat-ically connect with that exchange by the machine-driven impulse-sender, when the calling subscriber then dialing the number wanted would complete the connection by operating selectors, and a connector in the terminal exchange in the well-known manner.

Figs. 3 and i show one method of construction of our automatically operated or machine-driven impulse-sender and Fig. 5 shows the same in diagrammatic form associated in one way with a line switch of the Strowger type and the connections with the jacks on one side and the junction line on the other. is a fixed coil with a core 21 carried by brackets 25 and 31. An iron sheath forms the magnetic return which is free to rotate, the rear part 23 being formed as a driving wheel rotatable on the fixed shaft 2s is an impulse wheel rotatable on a shaft 32. The spring 29 has one end secured to the core 21 and the other end to the wheel30 and is so arranged that it keeps the wheel 30 normally away from the core and also returns it to normal after rotation. The wheel 30 is normally out of line of engagement with the springs 3-l but when the coil 20; is energized the wheel 30, which is wholly or partly of iron, is attract ed, but is kept from making actual contact with the sheath 22 or the core 21 by nonmagnetic stops 33. A power-driven shaft 26 by the pinion 39 rotates the sheath 22, 23 and the wheel 30 is now carried around so that the teeth 36 engage with the brush or wheel which is raised when passing over the teeth so as to close the contact 13-4A and open the contact at546, so that the circuit is interrupted according to the code of the wheel which as shown is :113. After all the teeth have been passed over the pin 37 opens the contact 38l2 and the contact of the pin 37 with the heavy spring 40 brings the wheels to rest. The opening of the contact 3842 puts the resistance -19 (Fig. 5) in circuit to reduce the current and to enable the wheel 30 to slip readily on the sheath 22 which is still rotating. vi hen current is removed from the coil 20 the spring 29 forces th wheel 30 away from the core so that it does not engage with the springs 34 on counter-rotation, and returns the wheel to the normal position. A number of these senders may be fitted on a common shaft and they may be fitted for one shaft driving two rows as shown by the second wheel 41. In busy exchanges these be continuously rotated during busy hours but during quiet hours and in small exchanges they may be controlled by a master magnet or other wellknown device so that they start when the plug is inserted.

In Fig. 5 P is a plug ending a junction or may be the calling plug of a pair. It is only necessary to show the circuit of the third conductor which is connected through resistance 51to battery 48 and earth. A junction line 61, 62 is shown with a multiple of three jacks M The bush wire of the jacks is carried in parallel through the coils of the impulse-sender 20 and the line switch 52 to earth. The multiple wires 63, 64: are carried to short-circuiting springs 43, H, and to opening springs 45, 46. The former reduce the resistance of the circuit and prevent disagreeable clicking in the callers receiver. The latter interrupt the circuit so as to allow the automatic switches to be actuated. The wires are extended to springs on the line switch which are normally open. lVhen the armature 53 is attracted the plunger 5 1 forces its insulated end 55 between the springs 57, so that one wire is joined through by springs 56, 57 and the other by springs 58, 59. When the plug P is inserted in a jack M and the sleeve 47 makes contact with the bush the circuit is shown through the two coils 20 and 52 in parallel. The circuit might be through 52 only, winding 20 z zratus and circuits specified are given merely by way of example it being obmodifications may be made. 1 claim and desire to secure by ietcers i atom in:

1 leph no system, an exchange, a other exchanges, junction lines saic first-mentioned exchange connection may be made with 1 er cxchauges, an automatic numerical said junction lines, a pluif jacks whereby connection may be made with said automatic switch, each of said jac hari associated with it means for send g particular numerical call so as to connect onl Y with a particular junction line or lines through said automatic switch.

2. In a telephone system, a callin subscrihers line connected to one exchange, a plu a ity of other exchanges, a called subscriocrs connected to one of said es, an intermediate exchange through whic connection is completed from said calling suhscrihefs line to said called suhscribcrs line, junction lines connecting said intermediate exchange to said other ex changes, a run ericai automatic switch at said intermediate exchange, jacks at said iirst-mentioned exchange, a junction line leading from said jacks to said automatic switch, an automatically operated calling means associated with said jacks and arranged so that the plugging into any par ticular one o" s l L i bib in c j aclas determines the nu mcrical operation of said automatic switch and thereby the junction line selected leading from said intermediate exchange to the one of aid other exchanges to which the called suhscribers line is connected.

3. ln telephone system, a calling subscribers line connected to one exchange, a plurality of other exchanges, a called subscr'hers line connected to one of said other oxchang I an intermediate exchange through which connection is completed from said c: ling subscrihe line to said called suhrhers line, unction luies connecting said intermediate exchange to said other exchanges, a numerical automatic switch at said intermediate exchange, groups of acks at saio first-mentioned exchange, groups of junction lines leading from said first-mentioned exchange to said intermediate exchange, each group of junction lines being associated with one of said groups of jacks, non-numerical automatic switches associated with each of said groups of jacks and dapted to connect a jack plugged into with an idle junction line of the corresponding group of junction lines, automatically operated calling devices associated with said jacks and arranged so that the plugging into any particular one of said jacks determines the numerical operation oi said automatic switch and thereby the junction line selected leading from said intermediate exchange to the one of said other exchan es to which the called subscribers line is connected.

4. in a telephone system, a calling subscribers line connected to one exchange, a plurality of other exchanges, a called subscribers line connected to one or" said other exchanges, an intermediate exchange through which connection is completed from said calling subscribers line to said called suhscribers line, junction lines connecting said intermediate exchange to said other exchanges, a numerical automatic switch at said intermediate exchange, groups of jacks at said first-mentioned exchange, groups of junction lines leading from said first-mentioned exchange to said intermediate exchange, each group of junction lines being associated with one or said groups of jacks, he dill'erent groups of junction lines being of dill'erent gage wire, non-numerical automatic switches associated with each of said groups or jacks and adapted to connect a jack plugged into with an idle junction line or the corresponding group of junction lines, automatically operated calling devices associated with said jacks and arran ed so that the plugging into any particular one of said jacks determines the numerical operation of said automatic switch and thereby the junction line selected leading from said intermediate exchange to the one of said other exchanges to which the called subscribcrs line is connected.

In testimony whereof we have aliixed our signatures in presence of two witnesses.

lVlliLlAM AITKEN. EGBERT AITKEN. Witnesses IN. S. CoLLINs, I. D. JAMEsoN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, I). C. 

